Firebug 1.8 API Changes

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Firebug 1.8 introduces set of API changes that can impact existing Firebug extensions. This page summarizes these changes and offers solution how to fix broken extensions.


RequireJS and AMD

Firebug source files are no longer loaded using <script> tags placed in a xul overlay (browserOverlay.xul). Firebug 1.8 uses RequireJS and Asynchronous Module Definition AMD. All files (there are still a few exception) follow the AMD syntax now (see an example).


  • FirebugChrome doesn't exist anymore, you need to use
  • FBTrace still exists
  • Firebug still exists
  • FBL still exists
  • Domplate still exists

XUL windows

Vast majority of Firebug extensions overlays firebugOverlay.xul so, the typical entry in the chrome.manifest (this is still the recommended way) file is following:

overlay chrome://firebug/content/firebugOverlay.xul         chrome://myext/content/myext.xul

These extension should have no problem to work with Firebug 1.8 since they are all running in browser.xul scope where all globals are defined by Firebug.

However, those extension that create new XUL windows or dialogs and use any Firebug global variables could face troubles, especially in cases where any of the following files (and others) are included.

<script type="application/x-javascript" src="chrome://firebug/content/trace.js"/>
<script type="application/x-javascript" src="chrome://firebug/content/xpcom.js"/>
<script type="application/x-javascript" src="chrome://firebug/content/chrome.js"/>
<script type="application/x-javascript" src="chrome://firebug/content/lib.js"/>
<script type="application/x-javascript" src="chrome://firebug/content/domplate.js"/>
<script type="application/x-javascript" src="chrome://firebug/content/firebug.js"/>

These files use AMD syntax and so, they must be loaded by a loader now. In order to use Firebug globals within another XUL scope you have two options:

  • Pass these globals from the browser window (browser.xul) to the XUL window/dialog through window arguments. This is the preferred way.
  • Get an existing browser window and access Firebug in it.

Window arguments:

var params = {
  Firebug: Firebug,
// This is how you open a dialog and pass parameters to it.
var parent =;
  "_blank", "chrome,centerscreen,resizable=yes,modal=yes",
// This is how you can get the parameters in onload of the XUL window
var params = window.arguments[0];
var Firebug = params.Firebug;
var FBL = params.FBL;

Access an existing browser window:

var Cc = Components.classes;
var Ci = Components.interfaces;
var windowMediator = Cc[";1"].getService(Ci.nsIWindowMediator);
var Firebug = windowMediator.getMostRecentWindow("navigator:browser").Firebug;
var FBL = windowMediator.getMostRecentWindow("navigator:browser").FBL;

JavaScript code modules

This section applies only to extension that explicitly import any of existing Firebug JS code modules.

Some JavaScript code modules has been transformed into AMD modules, but for now extension can still use the Components.utils.import to import them.

An example:

    Components.utils.import("resource://firebug/firebug-http-observer.js", scope);
  • "resource://firebug/firebug-http-observer.js": Firebug is using "firebug/http/requestObserver" AMD module.
  • "resource://firebug/firebug-trace-service.js": Firebug is using "firebug/lib/trace" AMD module.

The new way how to import these modules looks like as follows:

function (HttpRequestObserver)
    // TODO: module implementation

The other modules will be transformed into AMD too.

  • "resource://firebug/debuggerHalter.js"
  • "resource://firebug/firebug-annotation.js"
  • "resource://firebug/firebug-service.js"
  • "resource://firebug/observer-service.js"
  • "resource://firebug/storageService.js"

Removed API

TODO: This is only a rough list of changes, more explanation needed.

  • FBL.CCIN, FBL.CCSV and FBL.QI are obsolete, use "firebug/lib/xpcom"
  • HTMLLib is not part of Firebug namespace, you need to include "firebug/lib/htmlLib"
  • $STR, $STRP, $STRP, registerStringBundle, getStringBundle, getDefaultStringBundle, getPluralRule, internationalize and internationalizeElements are part of "firebug/lib/locale"
  • dispatch and dispatch2 are part of "firebug/lib/events" module
  • All preferences should be accessed through "firebug/lib/options" module
  • FBL.deprecated is now Deprecated.deprecated (firebug/lib/deprecated)
  • FBTrace comes from "firebug/lib/trace"
  • New modules: url, wrapper (don't use the API from FBL)
  • FBL.findNext and FBL.findPrevious no longer exist.
  • FirebugChrome namespace: getBrowsers, getCurrentBrowsers, getCurrentURI API removed and part of firefox/firefox module
  • There is a new <div> fbMainFrame (wrapping fbContentBox)
  • Firebug.getTabForWindow and getTabIdForWindow is removed, use firefox/window module (getWindowProxyIdForWindow).
  • FBL.openWindow, FBL.viewSource, FBL.getBrowserForWindow are part of firefox/firefox
  • FBL.ToggleBranch is now ToggleBranch.ToggleBranch
  • FBL.Continued removed.
  • FBL.isAncestorIgnored removed
  • FBL.ErrorMessage -> FirebugReps.ErrorMessageObj
  • FBL.fatalError removed
  • FBL.ErrorCopy -> FirebugReps.ErrorCopy
  • FBL.EventCopy -> DOM.EventCopy
  • FBL.Property -> FirebugReps.PropertyObj
  • FBL.findScripts -> Firebug.SourceFile.findScripts;
  • FBL.findScriptForFunctionInContext -> Firebug.SourceFile.findScriptForFunctionInContext;
  • FBL.findSourceForFunction -> Firebug.SourceFile.findSourceForFunction;
  • FBL.getSourceLinkForScript -> Firebug.SourceFile.getSourceLinkForScript;
  • FBL.getSourceFileByHref -> Firebug.SourceFile.getSourceFileByHref;
  • FBL.sourceURLsAsArray -> Firebug.SourceFile.sourceURLsAsArray;
  • FBL.sourceFilesAsArray -> Firebug.SourceFile.sourceFilesAsArray;
  • FBL.mapAsArray -> Firebug.SourceFile.mapAsArray;
  • FBL.NetFileLink -> Firebug.NetMonitor.NetFileLink


  • FBL.$ is deprecate, if you use it you should explicitly provide the document where the element is expected as the second parameter.
var elem = FBL.$("myElem", document);

FBL in XUL Windows

  • If you using FBL in separate XUL windows/dialogs, make sure you don't include files

<script type="application/x-javascript" src="chrome://firebug/content/xpcom.js"/> <script type="application/x-javascript" src="chrome://firebug/content/lib.js"/>

You need to pass FBL and Firebug globals through window arguments.

Or access it from the browser window:

const windowMediator = Cc[";1"].getService(Ci.nsIWindowMediator);
var FBL = windowMediator.getMostRecentWindow("navigator:browser").FBL;
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